Defining the Weld

By vb

Date 11-22-2003 19:24

Hi!

Just to make sure we are on the same page... I assume you are wanting to have a fillet weld on the side of the bolt that is sticking out.

If this is the case, you would only be able to have the leg length on the bolt to be 1/16". There are minimum requirements for fillet sizes in D1.1 which I am unaware of off hand - but I do know that it is good practice to have the size of the fillet leg to be atleast the size as the minimum thickness plate / pin you are trying to weld.

Since you are trying to weld a 3/4" dia pin - and a 1/4" plate - I would recommend your fillet leg size be a minimum of 1/4". Is there any way you can extend the pin length to extend 1/4" instead of 1/16"? If not, perhaps cutting out the 1/4" plate to allow for a bevel joint would be best.

Just my opinion!
Vicki

By strap85 Date 11-23-2003 02:30

Thanks so much for the responses.

To elaborate, the 1/4" plate is bolted to another member such that it is installed in a vertical position. The pin extends out of the plate roughly two inches and then a steel strap with a whole (slightly larger then pin diameter) is hung from the pin. The strap supports loads vertically only (or parallel with the plate/perpendicular with the pin). Because the hanging strap must be installed flush with the plate, a weld from the pin to the plate can not be made on the outside. However because the plate is being bolted to another member, the pin can not extend very far beyond the inside of the plate (1/16" is about as far as it can go).

Beveling out the plate is not a cost effective solution for this item. Our welder has been just welding all around the inside of the pin. We are testing this part to determine the load carrying capability and our current method is more than exceeding our expectations; however I am not sure what to call that type of a weld?

As you mentioned by definition it is a fillet weld, but because the weld is 4X less than the thickness of the smaller member, then I don't know if it qualifies for a fillet??? I also am trying to determine if it is necessary to provide special inspection on all parts fabricated in this fashion.

Thanks again for your insight.

By vb

Date 11-23-2003 03:44

As for the weld overexceeding your design - I assume you are drilling a hole aproximately 1" - 1 1/4" and then welding a "square groove weld" inbetween the plate and the pin.

As for switching to a 1/16" fillet weld - I am still uncertain if this would be acceptable by code - but my best advice would be to use a deep penetrating electrode. Deep penetration would help eliminate the faults concurring from shear stress - betweeen the weld and the pin (as that is the plane most of your forces will be focussed on) - and thus what I believe why many stress cracks occur right beside the weld.

I do not believe this is a practiced method, and would only recommend if you are building this for your ex-mother in law!!! lol!! And this brings me to special inspection. I would say it depends who you are building it for. Up here in Canada, we are only required to build to code - when we are building it for selling / retail purposes. Welcome to a world of entropy!!

Just remember, if this does break - there is always a chance of death (or even worse money wise - serious injury) and could come back to haunt you and/or your company. I would suggest to keep the square groove weld that works - and if you really wish to change the original for reasons as reducing the weld material / time, you may be able to go with a partial penetration weld. With this weld, you partially fill in the hole in the plate - instead of filling it in all the way - in this case 1/4" deep).

Good luck!
Vicki

By thirdeye (***)

Date 11-22-2003 19:29

By definition a fillet weld is a weld with a triangular cross section joining two surfaces that are approximately at right angles to each other.

Different codes specify the weld size along an edge based on the thickness of the base material (in your case 1/4"). Since the stickout of the pin is 1/16" this will be a very small fillet weld.

Since you did not discuss the application of this item or a particular code, is it an option to bevel the hole in the 1/4" plate and use a groove weld combined with a fillet weld in order to maintain the 1/16" stickout? Or is this overkill?

By strap85 Date 11-23-2003 02:31

By thirdeye (***)

Date 11-23-2003 04:04

Well, it is still a fillet weld. What code does your contract require?

In AWS D1.1 for example, the minimum weld size for prequalified joints (on 1/4" plate) would be 1/8" unless it is dynamically loaded in which case it would be 3/16". In your case the prequalified joint option cannot be used. You would have to run your own qualification tests.

Even a partial penetration weld with the 1/16" fillet weld to reinforce it may be better than just the fillet weld. I've seen 1/8" bevel prep done with a reamer. It takes no time at all. Anyway just a comment. Your testing may prove that this additional welding is not necessary.

By thirdeye (***)

Date 11-23-2003 04:15

Is the purpose of the 1/16" weld only to prevent the pin from slipping out of the hole? Are there any conditions that could lead to radial cracking of the weld? Once in service, is it possible for the pin to slip out of the hole if the weld were to fail? Can the weld be inspected while in service?

Just some afterthoughts ............

By thirdeye (***)

Date 11-23-2003 04:43

I did not notice the reply from vb above. Just to clarify, the pin is welded to the 1/4" plate on the side with the 1/16" stickout. 2" of the pin extends beyond the plate on the other side. A hanger with a 1-1/4" hole is installed on the pin and fits flush with the plate. The hanger is not welded to the pin or to the 1/4" plate. Please let me know if I'm off base. I'll try to pay better attention.......

Thanks

By DGXL

Date 11-23-2003 06:40

strap85 :
Based upon your posts, no matter how you slice it, it is a fillet welld.

Forum replies welcome.

By billvanderhoof (****)

Date 11-23-2003 06:44

This pin is loaded as a cantilever? That is there is no support on the end away from the quarter inch plate? Is it cyclically loaded? I don't know the loads involved but the weld sounds tiny (only a guess).

You could form a groove by drilling back from the off side of the plate with a larger drill (or a countersink) half way or so through the plate. As long as these plates are something liftable I would expect to do 50 or so in a hour (with a drillpress).

You could form a groove by pointing the end of the pin.

You could form a larger fillet by shortening the pin and then putting the weld on the inside of the hole. I'm not fond of this one, it's difficult to weld well and depends completely on the weld not failing.

The trouble with things that look strong like this is that, if accessable, sooner or later somebody will hook a come-along to it and use it to lift the counterweight off a forklift.
Bill